This application is a request for an RO3 award from NIMH to evaluate the acceptability and feasibility of rapid testing for HIV among substance abusers. Dr. Lally is in her second year on the full time faculty as an Assistant Professor of Medicine at Brown University. The clinical research training environment at the Miriam Hospital and Brown University is well-suited for an RO3. Substance abusers are at high risk for HIV disease not only because of needle sharing and "sharing of works" associated with injection drug use, but also because of high-risk sexual behavior among active substance abusers. Short-term substance abuse treatment (detoxification) is an excellent opportunity to interface with active substance abusers both for diagnosis of disease and linkage to medical care. Testing for HIV is not routinely offered at most detoxification centers. In contrast, we have routinely offered standard two visit HIV testing to inpatients at detoxification centers in Rhode Island and have found testing to be well received. Follow-up for HIV test results is a problem nation wide, and new technology now makes it possible to do rapid HIV testing so that immediate results are available. Quix(TM) is a rapid HIV test that can be easily administered in the detoxification setting. Feasibility and acceptability of rapid testing in this setting will be evaluated. We will administer an ACASI risk assessment to all study participants and then offer them HIV testing with both the rapid test, Quix(TM), and the standard FDA approved Orasure(R) test. We will test 220 people -55 young women (18-25), 55 older women (>25), 55 young men (18-25), and 55 older men (>25)- who are inpatients at a substance abuse detoxification center. Participants will be provided with their test results from the Quix(TM) test within minutes, and they will also be encouraged to receive the results of their Orasure(R) tests, which generally will be available within 2-3 days. Acceptability and satisfaction of rapid compared to standard testing as well as follow up rates will be evaluated among younger and older men and women and by risk profile.